Hi folks.
I was making some tests with UEFI and BIOS based systems about how the
Debian installer behaves.
Some questions/ideas:
1) BIOS Boot Partition... it seems you always create it with about 1MiB?
How did you choose that?
a) It seems like a lot, but is it sure that it will be enough in the
future?
b) Wouldn't it make some sense to use 4 MiB... so that could help a bit
for better alignment on 4K sector devices?
2) ESP... that always seems to have ~510 MIB? (or is it 512 MiB and my
tools just showed something wrong?)
Again, how did you choose that?
I guess it's enough... at least e.g. MS and Apple suggest smaller sizes,
see:
- http://technet.microsoft.com/en-us/library/dd799232%28WS.10%29.aspx#SystemPartitions
- https://developer.apple.com/library/mac/technotes/tn2166/_index.html
But... UEFI defines (AFAIK) the ESP to always be FAT32 (i.e. the specs
don't allow FAT12 or FAT16)... and there are rumours floating around
that this least to the minimum ESP size being exactly 512MiB, the
alleged minimum FAT32 partition/filesystem size:
Arch claims this, e.g.
https://wiki.archlinux.org/index.php/UEFI#EFI_System_Partition
Wikipedia gives this:
https://en.wikipedia.org/wiki/File_Allocation_Table#Size_limits
and from MS itself I found only values _for Windows XP_:
http://support.microsoft.com/kb/314463
In any case the minimum size seems to be dependant on the settings of
the FAT (cluster size e.g.).
So questions... in order to gain maximum compatibility we should format
the ESP always with FAT32... but depending on how we do that... is the
current size that is made, enough to fulfil the specs?
I mean normally, nothing should happen when we'd e.g. use a FAT32 fs
that is smaller than it's "official minimum size", cause apparently
Linux could already work with it... however one never knows which weird
UEFI implementor comes along and adds some crazy "check"...
Cheers,
Chris.
btw: please keep me CCed as I'm off list.